Telephone system



R. S WILBUR AND H. W. ULRiCH. TELEPHONE SYSTEM.

APPLICATION FILED nmzs. 1918.-

Patented D90. 2,1919.

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RAY S. 'WILBUR, OF LYNDHURST, AND HORACE W. ULRICH, OF EAST ORANGE, NEW .JERSEY, ASSIGNORS T WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Dec. 2, 193 Q of New Jersey, respectively, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to telephone transmission systems of the four Wire type in which two conductors outgoing from the station are employed for transmisslon of currents in one direction and two conductors incoming to the same station are employed for the transmission of currents in the opposite direction.

The object of this invention is to provide improved signaling means for systems of this character.

In a four wire transmission system the station at which the incoming and outgoing circuits terminate is provided with means for connection of these two circuits comprising the four wire system with a terminating circuit of the two wire type extending to a switchboard. In making such connection between the four wire and the two wire circuits, the outgoing circuit is inductively associated with the terminating circuit through a repeatingrcoil and the incoming circuit is connected with the terminating circuit by being bridged across themidpoints of the primary windings of the repeating coil. In such systems it is usual to provide for signaling from the switchboard end of the terminating circuit out over the outgoing C11- cuit, and also for signaling from the incoming circuit over the terminatlng circuit to the switchboard.

In attaining the object of this invention there is provided at the junction station of a system of this character two ringing response relays which are traversed by ringing current incoming to the junctlon station over either the incoming circuit or the terminating circuit. These ringingresponse relays control a switching relay in such a manner that when the switching relay is operated one ringing response relay and the incoming circuit are disconnected from the terminating circuit if ringing current is incoming to the junction station over such terminating circuit, while 'i the ringing current is transmitted to the junction station over the in'coming circuit theother ringing response relay and the terminating circuit are disconnected from the incoming circuit.

For a more complete understanding of this invention, reference should be had to the following description considered in connection with the' accompanying drawing illustrating one embodiment thereof.

In the drawing, there is shown so much of a typical four wire transmission system as is necessary for a complete understanding of the present invention. Line L represents the outgoing circuit of thefour wire transmission system, which is inductively connected with a terminating two wire circuit L through a repeating coil comprising the four primary windings 5 and the two secondary windings 6. The incoming circuit L of the four wire transmission system is connected through the windings of an autotransformer 7 and the contacts of a switching relay 8 to the midpoints of the primary windings 5 of the repeating coil. The autotransformer 7 is provided for the purpose of minimizing the reflection losses resulting from the transmission of telephonic currents from the incoming circuit L of one impedance into the terminating circuit L of another impedance. A ringing response re lay 9 bridged across the midpoints of the primary windings of the repeating coil and a ringing response relay 10 connected 'in circuit with the windings of the autotransformer 7 are adapted to be traversed by ringing current incoming to the junction station over either the tern'iinating circuit L or the incoming circuit L The windings of the relay 10 are connected in parallel with a condenser 11, which is of low impedance to telephonic currents, but of high impedance to ringing currents. denser 12 is provided for preventing the flow of direct current through the windings of relay 10. Relay 10 when energized, causes the release of aslow release relay 15 whose armature when fully retracted completes an operating circuit for the switclr lug relay 8 and a relay 16. Switching relay 8 in operating opens its normal contacts, thereby interrupting the connection between qnency of 133 cycles, depending'uponthe type of signaling receiving apparatus associated with the switchboard end of the terminating circuit. Ringing response rey la 9 upon beingenergized, causes the re easeof a slow release relaywhich,

upon the release of its armature, com-' pletes an operating circuit for the switching relay 8 and a relay 21. Relay 21 i causes the operation of a slow-operating and slow-releasing ringing relay 22 which controls the connection of ,a source of ringing current 23 with the outgoing circuit L This source of ringing currentr23 is preferably of a frequency of 133 cycles, in

order that the apparatus associated with the outgoing line may function properly. An

artificial balancing line L is provided for balancing the terminating'circuit L When telephonic currents are transmitted from the terminating circuit into the junction station, these currents are repeated through the repeating coil into the outgoing circuit L The ringing response relays 9 and 10 are of such impedance that they are not affected by currents of telephonic frequency whether transmitted from the terminating circuit L or from the incoming circuit L to the terminating circuit L Ringing current impressed upon the terminating circuit L at the switchboard end traverses the windings of both ringing response relays 9 and 10. mile the windings of both of these relays are traversed by current incoming 'over'the terminating circuit L yet relay 9 may operate prior to relay 10 and cause the release of relay 20. Relay 20 in releasing causes the operation of relays 8 and 21. Relay 8 in operating disconnects ringing response relay 10 and the outgoing circuit L,- from the terminating circuit L so that relay 10 will no longer be energized. S ould both ringing response relays operate simultaneously, relay 9 only will remain energized, for as soon as switching relay 8 operates, ringing current is dis connected from relay 10 which will release restoring relays 15 and 16 to normal condition. Relay 21 having operated, the'ringing relay 22 operates to connect the source of ringing current 23 with the outgoing circuit L Upon the cessation of ringing current incoming over the terminating circuit L to the junction station, relay 9 releases, relay 20.operates and relays 8, 21- and 22 release, re'c'sta-blishing the normal condition of the apparatus and system.

Ringing current incoming to the junction station over the incoming circuit L traverscs the windings of relays 9 and 10 and may cause the energization of both relays. If relay .10 operates before relay 9, relay 15 will release, causing the operation of relays 8 and 16. Relay 8 thereupon discomiects' ringing response relay 9 from the incoming circuit, whereupon relay 9 releases. The operation of relay 16 causes the energization of relay 17 which connects the source of ringing current 18 With the terminating circuit L If ringing response relays 9 and 10 operate simultaneously as the result of being traversed by current incoming over the incoming circuit L then relays 15 and 20 may release simultaneously. .Upon the release of either or both of these relays, switch relay 8 operates, disconnecting the ringing response relay 9 from the incoming circuit L This relay 9 thereupon releases, causing the operation of relay 20 and opening the operating circuit-of relay 21. Relay 22 is slightly slow in operating so that it does not have time to close its alternate contacts while relay 21 is energized,

From thisbrief description of the system embodying this invention and of its operation, it will be apparent, that only a comparatively small-amount of apparatus is required for relaying ringing current through the unction station between a terminating circuit of the two wire type and a transmission circuit of the four wire type.

What is claimed is: I i

1'. In a telephone system, in combination, two circuits extending from a junction station, two ringing response relays thereat adapted to be traversed by ringing current incoming to the station over either circuit, and a third relay controlled by either of the ringing .response relays and adapted when energized to disconnect the other from the circuit over which ringing current is incoming to the station.

2; In a telephone system, in combination,

two circuits extending from a junction station at which they are normally connected together, a ringing response relay connected with each circuit at the junction station and adapted to toe traversed by ringing current incoming to the station over either circuit, and a third relay controlled by either of the ringing responserelays and adapted when energized to disconnect the circuits.

3. In a telephone system, in combination, incoming and outgoing circuits, aterminatingcircuit operatively associated with the incoming and outgoing circuits at a junction station and extending therefrom, two ringing response relays at the junction station adapted to be traversed by ringing current transmitted to the station over either the incoming or the terminating circuit, a third relay controlled by either of the ringing response relays for disconnecting one ringing 1 ,seaeso response relay from the incoming circuit when current is transmitted thereoverand the other ringing response relay from the 'terminating circuit When ringing current is transmltted thereover to the station, a source of ringing current thereat, and means controlled by the ringing response relay which v remains connected to theterminating circuit for connecting the source of ringing current with the outgoing circuit.

' 4:. In a telephone system, in combination, incoming and outgoing circuits, a terminating circuit operatlvely associated therewith at a junction station and extending therefrom, a ringing response relay connected with the terminating circuit and a ringing response relay connected with the incoming circuit, both relays=being traversed by ringing current transmitted to the station over either of these circuits a third relay controlled by either of the ringing response relays for disconnecting the terminating and' incoming circuits, a source of ringing current, and means controlled by the continued RAY S. WILBUR. HORACE W. ULRICH. 

